Olivine Coating for All-Solid-State Battery Interface Stability
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Solution Overview
Problem
All-solid-state batteries using olivine-type positive electrode active materials and sulfide solid electrolytes face reduced actual battery capacity due to the formation of resistive layers at the interface during charging, which are damaged by repeated charging and discharging, leading to decreased cycling characteristics.
Innovation Solution
A positive electrode active material with a coating layer containing transition metals, lithium, phosphorus, and oxygen, and a transition metal-containing sulfide region with a thickness of 10 nm or less is applied, inhibiting the formation of resistive layers and enhancing lithium ion conductivity, allowing for improved battery capacity and cycling characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating layer is applied to the olivine-type positive electrode active material to prevent resistive layer formation, then battery capacity is improved, but the coating layer is easily damaged by repeated charging and discharging
Solution Approach 1:
The patent applies a composite coating layer comprising Li3PO4 and Li2SiO3 on the olivine-type positive electrode active material surface. This composite structure combines the protective properties of both materials to prevent resistive layer formation while maintaining structural integrity during charge-discharge cycles, thereby improving battery capacity without compromising coating stability.
Solution Approach 2:
The patent modifies the coating layer composition by incorporating both Li3PO4 and Li2SiO3 in specific proportions, and controls the thickness within 1-50 nm. These parameter optimizations enhance the coating's mechanical strength and adhesion, preventing damage during repeated cycling while maintaining its protective function against resistive layer formation.
2Strength
If the interface between olivine-type positive electrode active material and sulfide solid electrolyte is optimized by mixing and firing, then interface bonding is improved, but a resistive layer is formed during charging
Solution Approach 1:
The patent introduces a coating layer comprising Li3PO4 and Li2SiO3 as an intermediary between the olivine-type positive electrode active material and the sulfide solid electrolyte. This intermediate layer prevents direct harmful interactions that would form resistive layers during charging, while still maintaining optimal interface bonding for efficient lithium ion transfer, thus preserving battery capacity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables all-solid-state batteries to achieve theoretical capacity and demonstrate high cycling characteristics by preventing the formation of resistive layers and maintaining interface stability during charge-discharge cycles.
Implementation Method 1
a coating layer that coats all or a portion of the olivine-type positive electrode active material... preventing the formation of resistive layers and maintaining interface stability
Implementation Method 2
a transition metal-containing sulfide region having a thickness of 10 nm or less is present on the surface of the secondary particles... enhancing lithium ion conductivity
Data Source
AI summary
An all-solid-state battery having an olivine-type positive electrode active material and a sulfur solid electrolyte and a method for producing the all-solid-state battery is provided. The positive electrode active material is a positive electrode active material in which primary particles aggregate into secondary particles. The primary particles have an olivine-type positive electrode active material and a coating layer that coats all or a portion of the olivine-type positive electrode active material. The coating layer contains a transition metal derived from the olivine-type positive electrode active material, lithium, phosphorous and oxygen as components thereof, and the concentration of the transition metal is lower the concentration of the olivine-type positive electrode active material. A transition metal-containing sulfide region with a thickness of 10 nm or less and having sulfur and the transition metal derived from the olivine-type positive electrode active material is present on the surface of the secondary particles.